KR20150126535A - Methods for transceiving data in dual connectivity and apparatuses thereof - Google Patents

Abstract

[0001] The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting data under Dual Connectivity, and in which a PDCP (Packet Data Convergence Protocol) entity processes transmission data, Configuring a plurality of Radio Link Protocol (RLC) entities and dual connectivity for a radio bearer of the plurality of RLC entities, and transmitting at least one PDCP PDU (Packet Data Convergence Protocol Protocol Data Unit) to each of the plurality of RLC entities Receiving a response signal for at least one PDCP PDU transmitted from each of the plurality of RLC entities, and setting a transmission window based on the response signal.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for transmitting and receiving data under dual connectivity,

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting data under dual connectivity.

As communications systems evolved, consumers, such as businesses and individuals, used a wide variety of wireless terminals.

In a mobile communication system such as the current 3GPP series Long Term Evolution (LTE) and LTE-Advanced (LTE-Advanced), a high-speed and large-capacity communication system capable of transmitting and receiving various data such as video and wireless data, .

For such a high-speed, large-capacity communication system, a technique for increasing the capacity of a terminal using a small cell is required.

In this case, the terminal can transmit and receive data by configuring a dual connectivity using a small cell, and a technique for a high-speed data processing is required for the terminal and the base station to reduce loss of transmission / reception data under dual connectivity.

SUMMARY OF THE INVENTION In accordance with the above-described needs, the present invention provides a transmission method and apparatus for reducing data packet loss when a terminal and a base station transmit data under dual connectivity.

In addition, the present invention proposes a method and apparatus for sequentially processing data transmitted and received when transmitting and receiving data in a PDCP layer of a base station and a terminal.

According to an aspect of the present invention, there is provided a method of processing a transmission data by a Packet Data Convergence Protocol (PDCP) entity, the method comprising: transmitting a plurality of RLC (Radio Link Protocol) Transmitting at least one PDCP PDU (Packet Data Convergence Protocol Data Unit) to each of a plurality of RLC entities, receiving a response signal for the at least one PDCP PDU from the plurality of RLC entities And setting a transmission window based on the response signal.

According to another aspect of the present invention, there is provided a wireless communication apparatus including a PDCP (Packet Data Convergence Protocol) entity for processing transmission data, the PDCP entity including a PDCP entity for configuring dual connectivity and transmitting data received from an upper layer to a lower layer And a receiver for receiving a response signal to the transmitted data, wherein the PDCP entity includes a plurality of Radio Link Controllers (RLCs) configured for the dual connectivity with respect to one radio bearer, (PDCP PDUs) to each of the plurality of RLC entities, and sets a transmission window based on a response signal for the at least one PDCP PDU received from each of the plurality of RLC entities And a wireless communication device.

In the case of applying the present invention, it is possible to reduce the loss of data in consideration of delay in data transmission / reception through each base station under dual connectivity, and to process data in order.

In addition, when the present invention is applied, it is possible to transmit / receive data according to the correct packet order in the PDCP layer, and thus the ambiguity of the operation can be solved.

In addition, when the present invention is applied, it is possible to sequentially transmit a packet to a PDCP upper layer (for example, TCP, etc.), thereby increasing the transmission efficiency.

FIG. 1 is a diagram illustrating a state in which different base stations and terminals to which the present invention can be applied are dual connectivity.
2 is a diagram illustrating an example of a dual connectivity configuration to which the present invention can be applied.
3 is a diagram showing another example of a dual connectivity configuration to which the present invention can be applied.
4 is a diagram illustrating another example of a dual connectivity configuration to which the present invention can be applied.
5 is a diagram illustrating a structure of a user plane in two modes according to an embodiment of the present invention.
6 is a diagram briefly showing the PDCP entity from a functional point of view.
FIG. 7 is a functional view briefly showing a PDCP entity in a bearer split structure to which the present invention can be applied.
8 is a diagram illustrating a method of processing transmission data by a PDCP entity according to an embodiment of the present invention.
9 is an exemplary diagram illustrating a transmission window setting according to an embodiment of the present invention.
10 is a diagram illustrating a configuration of a wireless communication apparatus according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS Base transceiver system, an access point, a relay node, and the like.

That is, the base station or the cell in this specification is interpreted as a comprehensive meaning indicating a partial region or function covered by BSC (Base Station Controller) in CDMA, NodeB in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as a megacell, a macrocell, a microcell, a picocell, a femtocell, and a relay node communication range.

There are no restrictions on multiple access schemes applied to wireless communication systems. CDMA (Code

Division Multiple Access), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division

Multiple Access), OFDM-FDMA, OFDM-TDMA, and OFDM-CDMA. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

Herein, the user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word Do not. Hereinafter, the user terminal can be abbreviated as a terminal and instructed.

In a system such as LTE LTE-A to which the present invention can be applied, the uplink and the downlink are configured on the basis of one carrier or carrier pair to form a standard. The uplink and the downlink transmit control information through a control channel such as a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel And a data channel such as a Physical Downlink Shared CHannel (PDSCH), a Physical Uplink Shared CHannel (PUSCH), and the like.

The terms used in this specification will be briefly described as follows.

Dual Connectivity refers to an operation in which a UE receives resources from at least two or more different base stations connected in a non-ideal backhaul.

MeNB (Master eNB or Macro eNB) refers to a base station that operates as a mobility anchor by keeping at least the S1-MME interface with the CN in a dual connectivity situation.

SeNB (Secondary eNB or Small eNB) refers to a base station that is not a Master eNB but provides additional resources in a dual connectivity situation.

MCG (Master Cell Group) refers to a group of serving cells related to MeNB, and SCG (Secondary Cell Group) refers to a group of serving cells related to SeNB. Xn is the interface between MeNB and SeNB. The Pcell is a primary serving cell, the Scell is a secondary serving cell, and the sPcell (or pScell) is a special serving cell. In the SCG, a serving cell (serving cell of SCG with PUCCH).

EPC, which is a core network (CN), is composed of MME, S-GW and P-GW (Packet Data Network-Gateway). The MME has information on the access information of the terminal or the capability of the terminal, and this information is mainly used for managing the mobility of the terminal. The S-GW is a gateway having an E-UTRAN as an end point, and the P-GW is a gateway having a PDN as an end point. EPC is also referred to as CN in the present invention. A radio bearer (hereinafter, referred to as 'RB') is a path through which a packet is transmitted between a base station and a mobile station with a specific QoS through an EPC.

FIG. 1 is a diagram illustrating a state in which different base stations and terminals to which the present invention can be applied are dual connectivity. Figure 1 shows dual connectivity in a small cell scenario.

1, a base station (e. G., A macro eNB or a small eNB, 110,120) is widely deployed to provide various communication services such as voice, packet data, and so on. The wireless communication system includes at least one base station (e.g., a macro eNB or a small eNB, 110, 120). Each of the base stations 110 and 120 provides a communication service for a specific cell.

In addition, the base stations 110 and 120 can perform communication with a plurality of terminals in a specific cell.

A terminal 112 in a dual connectivity state with a different base station (e.g., a macro eNB or a small eNB 110, 120) to which the present invention can be applied is connected to each macro eNB (MeNB) 110 and And a small eNB (SeNB) 120, respectively. That is, the dual connection is an operation in which the terminal consumes radio resources provided by at least two different network points.

MeNB is an anchor base station that can be established with an MME and a mobility management entity (S1-MME) connection and is viewed from the viewpoint of a core network in the case of mobility such as handover between base stations (for example, 110). That is, changes between SeNBs are not involved in the core network. SeNB is a base station (e.g., 120) that is not a MeNB and is a base station that provides additional radio resources to a dual connected terminal. In this case, the macro eNB 110 may be a master eNB (MeNB) and the small eNB 120 may be a secondary eNB (SeNB). The opposite is also possible.

As shown in FIG. 1, one terminal receives a service from another base station and receives different data from each base station.

Although not shown in detail in FIG. 1, in order to perform the dual connectivity service, each of the eNBs can allocate a plurality of serving cells to different frequencies and set them to the UE. Serving cells corresponding to MeNB (macro eNB 110) are called MCG, and serving cells corresponding to SeNB (small eNB 120) are called SCG. That is, a plurality of serving cells may exist in one eNB.

In this specification, the term " dual connectivity " in this specification refers to a terminal that establishes an RRC connection with a terminal, terminates a base station or an S1-MME that provides a PCell serving as a reference for handover, and terminates a mobility anchor A serving base station is described as a master base station or a first base station.

The master base station or the first base station may be a base station providing macro cells and the base station providing any small cell in a dual connectivity situation between small cells.

In addition, a base station that provides additional radio resources to the terminal in a dual connectivity environment, which is distinguished from the master base station, is described as a secondary base station or a second base station.

The first base station (master base station) and the second base station (secondary base station) may each provide at least one cell to the terminal, and the first base station and the second base station may be connected through the interface between the first base station and the second base station. have.

In addition, for ease of understanding, a cell associated with a first base station may be referred to as a macro cell, and a cell associated with a second base station may be referred to as a small cell. However, in the small cell cluster scenario described below, the cell associated with the first base station may also be described as a small cell.

The macrocell in the present invention may mean at least one or more cells, and may be referred to as collectively referring to all the cells associated with the first base station. Also, a small cell may mean at least one or more cells, and may be referred to as collectively referring to the entire cell associated with the second base station. However, in a specific scenario, such as a small cell cluster as described above, it may be a cell associated with the first base station, in which case the cell of the second base station may be described as another small cell or another small cell.

The present invention relates to a method of transmitting / receiving data through dual connectivity in the small cell environment described above, and the small cell environment can mean communicating with a terminal using a low power node.

The small cell environment means an environment in which a node using a lower transmission power is deployed as compared with a general macro node, and can be deployed to cope with an increase in the number of terminals or an increase in traffic in a small area.

There are several scenarios in which a small cell is deployed in a dual connectivity environment to which the present invention can be applied.

2 is a diagram illustrating an example of a dual connectivity configuration to which the present invention can be applied.

Referring to FIG. 2, the macro cell 202 and the small cells 201 may have the same carrier frequency F1.

The first base station 210 providing the macro cell and the second base station 232, 234, 236 providing each small cell are connected through a non-ideal backhaul. The small cells 201 are built in an overlaid macrocell 202 network. An outdoor small cell environment and a small cell cluster 201 can be considered.

A terminal can receive a plurality of serving cells through a double connection with a macro cell and a small cell within a small cell cluster 201.

3 is a diagram showing another example of a dual connectivity configuration to which the present invention can be applied.

Referring to FIG. 3, the macro cell 302 and the small cells 301 may have different carrier frequencies F1 and F2.

The first base station 310 providing the macro cell and the second base station 332, 334, 336 providing each small cell are connected via a non-ideal backhaul. The small cells 501 are built in an overlaid macrocell 302 network. An outdoor small cell environment and a small cell cluster 301 may be considered.

A terminal may receive a plurality of serving cells through a double connection with a macro cell and a small cell in a small cell cluster 301. In this case, the frequencies of the respective serving cells may be different from each other by F1 and F2 as shown in Fig.

4 is a diagram illustrating another example of a dual connectivity configuration to which the present invention can be applied.

Referring to FIG. 4, a case where a plurality of small cells form a small cell cluster 401 can be considered. In this case, non-ideal backhaul is connected between the small cell base stations 410, 412, and 414 providing a small cell. An indoor small cell environment and a small cell cluster 401 are considered.

On the other hand, the dual accessibility means that one terminal uses radio resources of at least two base stations (eNB) together as in the above-described scenario. The base stations may be connected to an ideal backhaul that requires little time between transmissions between the base stations and may be connected to a non-ideal backhaul of several ms to several tens of milliseconds , And an exemplary embodiment of the present invention assumes a non-ideal backhaul connection.

In addition, the dual-intermittent environment can be further divided into a case with and without bearer splitting, and a case with bearer splitting is shown in Fig.

5 is a diagram illustrating a structure of a user plane in two modes according to an embodiment of the present invention.

In FIG. 5, two user plane (UP) structures may be possible for performing the dual connectivity service described in FIG. 1 to FIG.

Referring to FIG. 5A, in the UP 1A, the MeNB 510 and the SeNB 520 each include a separate PDCP (Packet Data Convergence Protocol) entity, a RLC (Radio Link Control) entity, a MAC (Medium Access Control) You can have an object.

5B, in the case of UP 3C, some of the resource bearers (RBs) serviced to the UE are serviced only by the MeNB 510 and the rest of the RBs are served by the MeNB 510 and the SeNB 520 at the same time. This shape can be called multi-flow or bearer split (or split bearer). The PDCP entity in the RB that performs the multi-flow may exist in the MeNB 510 and may have a separate shape on the RLC entity. That is, the PDCP SDU (Service Data Unit) becomes a PDCP PDU (Packet Data Unit) and can be distributed to the RNC entity of the MeNB 510 and the SeNB 520, respectively. The RLC entity of the SeNB 520 may distribute the PDCP entity of the MeNB 510 via the Xn interface, and may form a RLC SDU with the PDCP PDU delivered to perform the mode-dependent radio link control.

5, an Xn interface may be defined between the MeNB 510 and the SeNB 520, and the Xn interface may be implemented by various technologies such as an optical fiber, a digital subscriber line (DSL), a cable, a wireless backhaul . Tables 1 and 2 below show examples of backhaul performance of the Xn interface by each technique.

Backhaul Technology Latency  ( One way ) Throughput Fiber Access 1 10-30ms 10M-10Gbps Fiber Access 2 5-10ms 100-1000 Mbps Fiber Access 3 2-5ms 50M-10Gbps DSL Access 15-60ms 10-100 Mbps Cable 25-35ms 10-100 Mbps Wireless Backhaul 5-35ms 10Mbps-100Mbps typical, maybe up to Gbps range

Backhaul Technology Latency  ( One way ) Throughput Fiber Access 4 (NOTE 1) less than 2.5 us (NOTE2) Up to 10Gbps

Table 1 shows examples of non-ideal backholes, and Table 2 shows examples of ideal backholes. In Table 1 and 2, "Latency (One way)" represents one directional delay time and "Throughput" represents throughput per unit time.

As described with reference to FIG. 5, the dual connectivity can have two user plane structures. In the present invention, a method of transmitting and receiving data in the structure of FIG. 5B in which a bearer is split will be described.

5B, an RCP entity of a master base station and an RLC entity of a secondary base station may be connected to one PDCP entity.

5, in the LTE system in the dual connectivity, the wireless protocol layer includes a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (Medium Access Control) layer, and a physical layer (PHY) layer.

First, the PDCP layer is responsible for operations such as IP header compression / decompression and non-conversion / non-conversion.

6 is a diagram briefly showing the PDCP entity from a functional point of view.

The process of transmitting downlink data will be described with reference to FIG. The PDCP entity 600 of the base station receives the PDCP SDU (Service Data Unit) from the upper entity and performs sequence numbering and header compression. In this case, header compression can be performed only when it is user plane data.

Then, the PDCP entity 600 of the base station performs integrity protection and encryption of the packet 601 associated with the PDCP SDU, adds the PDCP header, and transmits the PDCP header to the lower layer.

If the PDCP entity 600 of the base station 600 does not perform the integrity protection and encryption for the packet 602 that is not related to the PDCP SDU, the PDCP entity 600 may transmit the PDCP header to the lower layer by adding the PDCP header.

The generated PDCP PDU (hereinafter, referred to as 'PDU') is transmitted to the PDCP entity 610 of the UE through the wireless interface.

In operation of the PDCP entity 610 of the UE, the PDCP header is removed from the received PDCP PDU, and the integrity protection and encryption of the packet 611 associated with the PDCP SDU is performed. It may not perform the integrity protection and encryption operation in the case of the packet 612 not related to the PDCP SDU.

Thereafter, the PDCP SDU can be transmitted to the upper layer after releasing the header and detecting duplication.

The conventional PDCP entity can perform data transmission and reception by performing the above function when the PDCP entity is not a split bearer.

One PDCP entity is a general configuration method when one RLC entity is not connected to a spill-bearer. In this case, the RLC entity supports sequential or in-sequence transmission to the PDCP entity. In other words, except for a special case, the sequence number of PDCP PDUs received from the RLC entity follows the ascending order, and after receiving a PDCP PDU corresponding to a large sequence number (SN) The PDCP PDU corresponding to the sequence number is not transmitted.

However, when the split bearer is configured under dual connectivity as in the present invention, since a plurality of RLC entities are connected to one PDCP entity, the operation thereof may be changed.

FIG. 7 is a functional view briefly showing a PDCP entity in a bearer split structure to which the present invention can be applied.

Referring to FIG. 7, in a bearer split structure, a PDCP entity 700 of a base station can perform a routing function to distribute PDCP PDUs to an RLC entity of a master base station or an RLC entity of a secondary base station. In this case, the PDCP entity 700 of the base station can distribute the PDCP PDUs in consideration of the radio channel quality and load of the master base station or the secondary base station.

The PDCP entity 710 of the UE can receive the PDCP PDUs from the RLC entity configured by peering with the RLC entity of the master base station and the RLC entity of the secondary base station and the RLC entity configured by peering.

The routing function may exist inside the PDCP entity 700 or may exist outside the PDCP entity 700 and be implemented in the base station.

In this case, the PDCP entity 710 of the UE receives a PDCP PDU from a plurality of RLC entities, and each PDCP PDU includes a non-ideal backhaul between the master base station and the secondary base station, a radio channel state of the master base station, Lt; / RTI > can be received with different delays according to the < RTI ID =

Accordingly, it is necessary for the PDCP entity 710 of the UE to organize PDCP PDUs received from a plurality of RLC entities in order and to perform a processing operation on PDCP PDUs that are not received or are missing in sequence. Accordingly, the PDCP entity in the bearer split structure can perform a reordering function.

The RLC layer reconfigures packet data units (PDUs) generated from the PDCP layer to an appropriate size to perform ARQ operations and the like, and rearranges the order of the RLC PDUs whose order is reversed in the ARQ process. Here, the term PDU mentioned means packet data output from a specific protocol layer. Hereinafter, the apparatus of the RLC layer is referred to as an RLC entity.

The basic function of the RLC layer is to guarantee the QoS of each radio bearer (RB) and to transmit the data accordingly. Since the RB service is a service provided by the second layer of the radio protocol to the upper layer, the entire second layer influences the QoS, but the influence of the RLC is particularly great. In order to guarantee the QoS inherent to the RB, the RLC sets independent RLC entities for each RB and provides three modes of transparent mode (TM), non-response mode (UM) and response mode (AM) to support various QoS . Since the three RLC modes have different QoSs to be supported, there is a difference in the operation method, and the detailed functions are also different. Therefore, it is necessary to examine each operation mode (TM, UM and AM) of the RLC in more detail.

The TM RLC is a mode in which no overhead is given to the RLC SDU received from the upper layer when constructing the RLC PDU. That is, since the RLC transparently passes through the SDU, the TM RLC is called a TM RLC, and the TM RLC plays the following role in the user plane and the control plane. Since the data processing time in the RLC is usually short in the user plane, the TM RLC is responsible for the transmission of real-time circuit data such as voice or streaming in the circuit service domain (CS domain), and in the control plane, Since there is no overhead, it carries the transmission of the RRC message from the unspecified terminal in the case of the uplink (uplink), and the transmission of the RRC message broadcasted to all terminals in the cell in the downlink case.

Unlike the transparent mode (TM), a mode in which overhead is added in the RLC is called a non-transparent mode. In the non-transparent mode, a non-response mode (UM) There is an answer mode (AM). The UM RLC attaches a PDU header including a sequence number (SN) to each PDU (Protocol Data Unit), thereby allowing the receiver to know which PDU is lost during transmission. Due to this function, the UM RLC is mainly responsible for transmission of broadcast / multicast data on the user plane, transmission of real-time packet data such as voice (VoIP) or streaming in the PS domain, The RRC message is transmitted to the specific terminal or the specific terminal group in the RRC message.

Also, the AM RLC, which is one of the non-transparent modes, constructs a PDU by attaching a PDU header including the SN in the PDU configuration like the UM RLC. However, unlike the UM RLC, the receiving side acknowledges the PDU transmitted from the transmitting side, There is a big difference. The reason why the receiving side responds in the AM RLC is to request the transmitting side to retransmit the PDU that it has not received, and this retransmission function is the most important feature of the AM RLC. As a result, the AM RLC is intended to guarantee error-free data transmission through retransmission. For this purpose, the AM RLC is mainly used to transmit non-real time packet data such as TCP / IP in the packet service area And the control plane is responsible for the transmission of the RRC message, which must be acknowledged in the RRC message to be transmitted to the specific UE in the cell.

The MAC layer is connected to a plurality of RLC layer devices configured in the UE, multiplexes RLC PDUs into MAC PDUs, and demultiplexes RLC PDUs from MAC PDUs.

The physical layer performs channel coding and modulation on the data of the upper layer, transfers the OFDM symbol to the OFDM symbol and transmits the OFDM symbol on the wireless channel, demodulates the OFDM symbol received on the wireless channel, decodes the channel, .

The present invention provides a method and apparatus for lossless data processing in a dual connectivity situation when a terminal and a base station constituting the PDCP, RLC, MAC, and PHY layers transmit and receive data.

In the following description of the present invention, it is assumed that the RLC entity is an AM mode and the PDCP entity provides the routing and reordering functions. However, the present invention is not limited to such an example, and can be applied to both modes of the RLC entity and functions of the PDCP entity.

In order to facilitate understanding, the base station transmits downlink data to the terminal and the terminal receives and processes the corresponding data from the base station. In the present invention, the terminal transmits uplink data to the base station, It is possible to apply the same to the case of receiving and processing.

As described above, when a macro cell and a small cell are constructed as individual base stations through a non-ideal backhaul in a dual connectivity situation, a problem may arise in which a plurality of carriers can not be effectively used due to a non-ideal backhaul delay. That is, since data transmitted through the secondary base station includes a non-ideal backhaul delay as compared with data transmitted through the master base station, if a single radio bearer is transmitted through two base stations, There is a problem that data out of order is always received from a PDCP entity to be processed. However, in the conventional PDCP layer for processing data transmitted through a single base station, data is sequentially received through the RLC layer in the same base station, so that this problem does not occur.

Accordingly, in the present invention, a method for solving a problem in which PDUs out of order are processed in a PDCP entity when a bearer is split and configured in a dual connectivity environment, and a method for solving the problem, A method and an apparatus for transferring the RLC entity to the RLC entity of the secondary base station will be described.

In the following description of the present invention, a PDCP entity shall be described as a receiving PDCP entity when receiving data, and a transmitting PDCP entity when the PDCP entity transmits data. This is for the sake of understanding only because it is classified according to the operation of the PDCP, so it is not limited to this term. In addition, one PDCP entity can transmit and receive data, and in this case, the PDCP entity and the PDCP entity must be understood as a PDCP entity. In addition, both the receiving PDCP entity and the transmitting PDCP entity can be implemented in one device (terminal or base station). That is, the receiving PDCP entity and the transmitting PDCP entity are merely a division for convenience of understanding from the functional point of view, and thus are not construed as being limited thereto.

As described above, when transmitting data from the base station to the mobile station in the dual connectivity situation, the radio resources of the secondary base station can be used.

In this case, the UE may configure an RLC entity configured by being mapped to an RLC entity of the master base station and an RLC entity configured by being mapped to an RLC entity of the secondary base station. Also, one PDCP entity can be configured in a bearer split structure.

Accordingly, the PDCP entity receives the PDCP PDUs delivered from a plurality of RLC entities, and constructs the SDUs in order of the lost PDUs or the late arriving or early arriving PDUs. The manner in which the PDCP entity performs the reordering may be considered in various ways.

In detail, a method of sequentially processing PDCP entities according to the present invention upon receipt of data will be described with reference to respective embodiments.

Embodiment 1: Performing a reordering operation based on a reordering timer and a window.

The receiving PDCP entity may perform reordering based on the reordering timer and the window. Specifically, for example, for a PDCP PDU received from a lower layer, the receiving PDCP entity checks the SN (Sequence Number) of each PDCP PDU. If the received PDCP PDUs are sequentially received based on the SN, the receiving PDCP entity performs at least one of the above-described decoding, integrity verification, header decompression, and duplication detection and delivery for the corresponding PDCP PDU and transfers the PDCP PDU to the upper layer.

If some SNs are missing in the process of confirming the SN of the received PDCP PDU, the receiving PDCP PDU sets the window based on the SN of the specific PDCP PDU. For example, the window is set based on the last SN of the received PDCP PDU including the SN of the missing PDCP PDU. The size of the window to be set can be variously set, and the size of the window may be changed depending on the setting. For example, when the SNs of the received PDCP PDUs are 100, 101, 102, and 110, the window may be set in the forward direction based on the 110 according to a preset window size. For example, when the window size is 10, windows 101 to 110 can be set.

The receiving PDCP entity initiates a reordering timer when a window is set. And waits to receive a missing PDCP PDU that has not been received while the reordering timer is in progress. If a missing PDCP PDU is received before the reordering timer expires, the reordering timer is terminated, and the PDCP SDU is delivered to the upper layer by performing the above-described decryption and the like.

If a reordering timer receives a PDCP PDU having an SN out of the window during operation, it may be stored in a buffer or discarded based on the SN.

The receiving PDCP entity may process the received PDCP PDUs in the window once the reordering timer expires and set the window again for the next PDCP PDUs stored in the buffer or received from the lower layer.

That is, the receiving PDCP entity may set a window and operate a reordering timer to process out-of-order PDCP PDUs. In addition, when the reordering timer expires, the reordering timer can operate again after the window is moved based on a specific PDCP PDU. By repeating this series of processes, the receiving PDCP entity can process data packets received from a plurality of RLC entities in order.

The operation of the above-described first embodiment will be described with reference to an example using variables.

The receiving PDCP entity can maintain the following window variable information.

VR_PR: Maintains the SN of the earliest PDCP PDU considered for reordering in the split bearer.

VR_PX: Indicates the SN value of the PDCP PDU triggered by the reordering timer in the split bearer.

VR_PH: Maintains the SN value along the SN of the PDCP PDU having the highest SN among the plurality of PDCP PDUs received from the split bearer, and is served to the top of the reordering window.

The operation of the first embodiment will be described. The receiving PDCP entity maintains a receiving window according to VR_PH.

When the receiving PDCP entity receives a PDCP PDU from a lower layer, the PDCP PDU is received when the received PDCP PDU SN is greater than VR_PR and less than VR_PH (VR_PR <SN <VR_PH) And discards the corresponding PDCP PDU if it is smaller than VR_PR. Otherwise, the receiving PDCP entity may store the received PDCP PDU in the receiving buffer.

If the SN of the received PDCP PDU is out of the reordering window, VR_PH is updated to the SN of the PDCP PDU described above plus one.

If VR_PR is out of the reordering window, VR_PR is set to a value obtained by subtracting the window size from VR_PH.

If the receive buffer includes an SN of a PDCP PDU such as VR_PR, VR_PR is updated to the SN of the first PDCP PDU larger than the current VR_PR not received. That is, the value after the SN of the received PDU received last in the current state is updated to VR_PR.

If the reordering timer is running, stop the reordering timer when VR_PX is less than or equal to VR_PR, or when VR_PX is out of the reordering window and VR_PX is not equal to VR_PH. That is, if all missing PDUs (with a small SN) that should be received in order before the out-of-order PDCP PDUs are received before the reordering timer expires, the reordering timer is stopped. In other words, if the PDCP PDUs out of the above-described order can be processed in order, the reordering timer is stopped.

If the reordering timer is not running and VR_PH is greater than VR_PR, the reordering timer is started. That is, if there is a PDCP PDU considering reordering in the PDCP entity of the UE, a reordering timer is started. Then set VR_PX to VR_PH.

While the timer is in operation, the PDCP entity waits for the missing PDCP PDU.

If all missing PDUs are received before the reordering timer expires, the reordering timer is stopped. That is, if the PDCP PDUs out of the above-described order can be processed in order, the reordering timer is stopped.

When the reordering timer expires, the PDCP entity updates the VR_PR to the SN of the first PDCP PDU equal to or greater than the unreceived VR_PH.

If missing PDCP PDUs are not received or the reordering timer is not in operation until the reordering timer expires, that is, if the received PDCP SN is less than the next expected PDCP SN (received PDCP SN < Next_PDCP_RX_SN), HFN is set to 1 And performs decryption on the PDCP PDU using the count based on the HFN and the received PDCP SN (COUNT). Then, the next expected PDCP SN is set to a value obtained by adding 1 to the received PDCP SN. If the next expected PDCP SN is greater than the maximum PDCP SN, then set the next expected PDCP SN to zero and increase HFN by one. Header compression and delivers the PDCP SDU to the upper layer.

Second Embodiment: Performing a reordering operation based on a reordering timer.

The receiving PDCP entity checks the SN of a PDCP PDU received sequentially or in bulk, and if there is no missing PDCP PDU sequentially, it transmits the PDCP PDU to an upper layer through a decoding process or the like.

If a missing PDCP PDU is found in the identified SN, a reordering timer is started. Since the previous PDCP PDU has been received in order based on the SN of the missing PDCP PDU, the PDCP PDU is delivered to the upper layer through decoding or the like.

If all the missing PDCP PDUs are received during the reordering timer operation, the reordering timer is stopped and transmitted to the upper layer through a process such as decoding.

If the reordering timer expires, the reordering timer is concatenated with a count value less than the count value of the triggered PDCP PDU, and delivers all stored PDCP SDUs to the upper layer. Alternatively, the reordering timer is associated with the count value continuously connected from the count value of the triggered PDCP PDU, and delivers all stored PDCP SDUs to the upper layer.

Also, when the reordering timer expires, the receiving PDCP entity sets the SN of the PDCP PDU of the last PDCP SDU delivered to the upper layer to the last submitted PDCP SN.

The receiving PDCP entity also starts a reordering timer when the reordering timer has expired and at least one PDCP SDU associated with the split bearer has been retained in the reordering buffer and the HFN (Hyper frame number) of the received PDCP PDU The SN of the next PDCP PDU can be set to the reordering PDCP SN.

Through this operation, the receiving PDCP entity can process the PDCP PDUs received from the plurality of RLC entities in order.

In addition to the first and second embodiments, the PDCP PDU can perform a reordering operation in various manners. For example, the operations of the first embodiment and the second embodiment may be mixed to perform the reordering operation. As another example, the receiving PDCP entity may perform a reordering operation similar to the reordering operation performed by an existing RLC entity.

However, even if the receiving PDCP entity performs reordering on the received data using the above-described method, a problem may occur in a certain situation. For example, in a dual connectivity situation where a bearer is split, the delay due to the interface between the master base station and the secondary base station and the delay due to the channel state of each of the master base station and the secondary base station must be considered. Therefore, when the delay is considered, it may happen that a particular data packet arrives too early or too late.

Thus, in a situation where the bearer is split through the master base station and the secondary base station, a difference may occur between the transmission side and the reception side by using the security algorithm. For example, HFN, one of the input parameters used in the security algorithm, may be different on the transmitting side and the receiving side. If this error occurs, if the PDCP entity decodes the MASK using the erroneous HFN, the PDCP entity continuously discards the received PDCP PDUs by continuously generating an error when restoring the header. The RB (i.e., Signaling RB) of the control plane decodes the received PDCP PDU and performs integrity verification. At this time, when decoding with MASK using wrong HFN or comparing with wrong XMAC-I, an error occurs consistently in integrity verification and the received PDCP PDUs are continuously discarded. Accordingly, when a security error occurs, the terminal and / or the network regards this as a serious problem, re-establishing the RRC connection between the terminal and the network, and resetting the security. When the RRC connection is re-established, all SRBs and DRBs are also re-established.

In this way, if the HFN is erroneously set, the receiver can not properly receive the data and performs an unnecessary RRC connection re-establishment operation.

Therefore, even if the receiving PDCP entity performs reordering as described above, if the HFN correction can not be accurately performed, the above problem may occur in data reception. HFN correction means an operation in which the receiving PDCP entity adds 1, subtracts 1, or leaves the HFN value to the SN of the received PDCP PDU. For example, the receiving PDCP entity sets a window for HFN correction on the front and back sides based on the next SN of the PDCP SN submitted to the upper layer. As an example, the total window size set for HFN correction may be set equal to the number of SNs based on the bits of the SN. Thereafter, it is possible to perform an operation of adding or subtracting 1 from the HFN value to PDCP PDUs received outside the window or received in the window.

However, even if the conventional HFN correction is performed, an error in the HFN value may occur due to a large number of delays and channel differences in the bearer split dual communication environment. For example, when the channel delay of the master base station is smaller than that of the secondary base station, the mobile station can first receive data received through the master base station. That is, the data received through the secondary base station can be received late by combining the delay transmitted from the master base station to the secondary base station and the channel delay of the secondary base station.

For example, a primary PDCP PDU to be received by the receiving PDCP entity through the RLC entity mapped to the RLC entity of the master base station is SN 0 to 500 in the HFN 0, and is received through the RLC entity mapped to the secondary base station It may happen that the secondary PDCP PDUs to be received in the PDCP entity are SN 501 to 1023 in HFN 0 and SN 0 to 600 in HFN 1. Also, the tertiary PDCP PDU may be transmitted through the RLC entity of the master base station, and the PDCP PDU may be up to SN 700 to 900 in HFN 1. In this case, after the primary PDCP PDU is received, the tertiary PDCP PDU may be received first by a delay or the like before the secondary PDCP PDU is received. The receiving PDCP entity sets a window for HFN correction after receiving the primary PDCP PDU, and then performs HFN correction on the received PDCP PDU. However, as the third PDCP PDU is received before the second PDF, it is necessary to add one HFN, but a problem of determining HFN 0 may occur.

For example, the same problem as described can not be solved by the reordering process according to the first and second embodiments of the above-described reception PDCP entity. However, in order to solve such a problem, it is possible to consider setting the window size for reordering as described above or setting the reordering timer to be long.

However, in such a case, there may arise a problem that the data reception rate and the processing speed can be reduced.

Therefore, the operation of the transmission PDCP entity according to the present invention for solving the HFN error described above will be described below in detail.

As described above, in the present invention, it is assumed that a plurality of RLC entities connected to a PDCP entity of a base station are AM RLCs. For convenience of description, downlink data transmission when two AM RLC entities and a PDCP entity are connected Will be described. In other words, the downlink data transmission operation of the PDCP entity of the master base station connected to the AM RLC entity of the master base station and the secondary base station in the bearer splitted dual connectivity will be described as an example. It goes without saying that the present invention can also be applied to a case where a terminal transmits uplink data to a base station.

8 is a diagram illustrating a method of processing transmission data by a PDCP entity according to an embodiment of the present invention.

A method of processing a transmission data by a Packet Data Convergence Protocol (PDCP) entity according to an embodiment of the present invention includes configuring a plurality of RLC (Radio Link Protocol) objects and dual connectivity for one radio bearer Transmitting at least one PDCP PDU (Packet Data Convergence Protocol Data Unit) to each of a plurality of RLC entities, receiving a response signal for at least one PDCP PDU transmitted from each of the plurality of RLC entities, And setting a transmission window based on the response signal.

For example, referring to FIG. 8, a wireless communication apparatus including a PDCP entity configures dual connectivity. A PDCP entity may include both a transmission and a reception function and is described below as a transmission PDCP entity in terms of transmission data processing.

The wireless communication apparatus including the transmission PDCP entity described above can configure dual connectivity as shown in FIGS. 1 to 5 (S810).

For example, the transmitting PDCP entity of the master base station may be connected to the RLC entity of the master base station and the RLC entity of the secondary base station in constructing the dual connectivity. In this case, a connection with a plurality of RLC entities may be established for one radio bearer in the bearer split structure, and a connection between the master base station and the secondary base station may be established through the X2 interface.

In a situation where dual connectivity is configured, the transmitting PDCP entity may transmit at least one PDCP PDU to each of a plurality of RLC entities (S820). For example, the transmitting PDCP entity may distribute PDCP PDUs to a plurality of RLC entities through a routing function in a bearer-split structure as shown in FIG.

Thereafter, the transmitting PDCP entity may receive a response signal from each of the plurality of RLC entities (S830). For example, a plurality of RLC entities may be configured in an Acknowledged Mode (AM), and each of the plurality of RLC entities transmits a PDCP PDU received from a transmitting PDCP entity to a receiving apparatus through a lower layer and an interface. The AM RLC entity may then receive response information for data transmitted from the receiving device. For example, when a base station transmits downlink data to a terminal, when a packet of the corresponding downlink data is normally received in the terminal, the terminal sends a response to the normally received data packet to the base station. Request retransmission. Thus, the AM RLC entity can obtain information on whether a packet of the transmitted data has been normally received by the receiving apparatus. Accordingly, the transmission PDCP entity according to the present invention can receive a response signal for a PDCP PDU transmitted from each of the plurality of RLC entities. The response signal may include information on whether or not each PDCP PDU is received, and may be received in the form of a PDCP status report or the like. That is, each of the plurality of RLC entities can transmit a response signal to the PDCP entity based on the response information, upon receiving the response information for the transmission data from the receiving apparatus.

In addition, the response signal may include information on a PDCP PDU that has been confirmed to be received by the receiving apparatus among at least one PDCP PDU. Alternatively, it may include information on PDCP PDUs not received at the receiving apparatus. Alternatively, it may include both information on the received PDCP PDU and information on the PDCP PDU that has not been received.

The transmitting PDCP entity may include setting a transmission window based on the response signal (S840).

The transmission window may mean a monitoring interval that is set to a predetermined size including a PDCP PDU whose reception is not confirmed based on the above-described response signal in the transmission PDCP entity. For example, the transmission window may be set based on a sequence number (SN) of at least one unidentified PDCP PDU whose reception has not been confirmed by the receiving apparatus and a total number of sequence numbers that can be assigned to the PDCP PDU .

In this case, the transmitting PDCP entity may check whether the PDCP PDU included in the transmission window range is received, and store the PDCP PDU for the PDCP SDU received from the upper layer out of the transmission window in the buffer. If the PDCP PDU whose reception is confirmed by the response signal is changed, the transmission window is reset, and the PDCP PDU stored in the buffer can be transmitted to the RLC entity. Therefore, the transmitting PDCP entity can transmit only a certain range of PDCP PDUs to the lower layer, and when the normal receiving information in the receiving device for the transmitted PDCP PDU is received, the transmitting PDCP entity can further transmit the PDCP PDU stored in the buffer. The contents related to the transmission window setting will be described in more detail with reference to FIG.

9 is an exemplary diagram illustrating a transmission window setting according to an embodiment of the present invention.

The transmission window is set to be equal to or larger than the smallest sequence number based on the PDCP PDU having the smallest sequence number among at least one unidentified PDCP PDU and the size of the transmission window is set to half of the total number of sequence numbers allocated to the PDCP PDU . Or for half or more of the total number of sequence numbers for dual connectivity. For example, the size of the window in the PDCP entity of the terminal may be informed to the terminal by dedicated signaling (RRC)

Referring to FIG. 9, a transmitting PDCP entity may forward a PDCP PDU to each RLC entity. Also, it is possible to receive a response signal including information on normal reception of the PDCP PDU.

In FIG. 9, the identification numbers such as n-2 and n-1 indicate the SN of each PDCP PDU. n-2 and n-1 are PDCP PDUs transmitted to the lower layer and receiving a response signal normally received by the receiving apparatus. n indicates a PDCP PDU that has been transmitted from the transmitting PDCP entity to the lower layer but has not yet received a response signal for normal reception in the receiving device. N + 1 and n + 2 denote PDCP PDUs that have not yet been transmitted to the lower layer.

In the exemplary situation shown in FIG. 9, the transmitting PDCP entity may transmit only the corresponding PDCP PDU to the lower layer while waiting for a response signal of the PDCP PDU in the transmission window.

First, in the T0 time, the transmitting PDCP entity transmits the PDCP PDUs of n-2 to n to the lower layer, receives the acknowledgment response of the PDCP PDU corresponding to n-2 and n-1, A response to the PDCP PDU is not received. Therefore, in setting the transmission window, the transmission PDCP entity sets the transmission window 901 based on n having the smallest sequence number (SN) among unidentified PDCP PDUs.

At the time T1, the transmission PDCP entity has delivered the PDCP PDUs corresponding to n + 1 and n + 2 to the lower layer, but has not yet received the acknowledgment for the PDCP PDU corresponding to n, Is maintained.

At time T2, the transmitting PDCP entity received PDCP PDUs corresponding to n and n + 1 and received PDCP PDUs corresponding to n + 3 and n + 4 to the lower layer. However, since a response to the PDCP PDU corresponding to n + 2 has not been received, the transmission window 903 is set starting from the n + 2 sequence number.

At time T3, the transmitting PDCP entity has received the acknowledgment response for the PDCP PDUs corresponding to n + 2 and n + 4, but has not received the acknowledgment for the PDCP PDU corresponding to n + 3. Accordingly, the transmission PDCP entity sets the transmission window 904 from PDCP PDUs corresponding to n + 3 having the smallest sequence number among at least one PDCP PDU set whose reception is not confirmed.

As described for example in FIG. 9, the transmitting PDCP entity may establish a transmission window and set or reset a transmission window based on the acknowledgment signal including the information of the receiving side of each PDCP PDU.

On the other hand, the transmission window size may be set to a half of the total number of sequence numbers that can be allocated to the PDCP PDU. Or may be set to a natural number greater than or equal to 1 by setting.

Through this operation, the PDCP entity transmits only the PDCP PDUs within the transmission window range, thereby preventing the occurrence of the HFN correction problem.

As another example, the PDCP entity according to the present invention may control the step of receiving the above-mentioned response signal and the step of setting the transmission window to be activated or deactivated based on the mode of a plurality of RLC entities. In other words, the response signal can be received and the window can be set only when the mode of the RLC entity is the response mode. Or to activate or deactivate at least one of the steps depending on whether the mode of the RLC entity is a non-responsive mode (UM) or a transparent mode (TM).

As another example, when setting the transmission window of the PDCP entity, it is possible to separately set a processing method for the PDCP PDU that has not been delivered to the lower layer or has not been delivered. For example, a PDCP PDU or a deleted PDCP PDU that can not be transmitted from a transmitting PDCP entity to a lower layer can not receive a response acknowledgment, so that a transmission window can not be changed and ambiguity may arise.

Therefore, in setting the transmission window, the transmission PDCP entity according to the present invention can process the PDCP PDU that has not been delivered to the lower layer without allocating the sequence number or receiving the response signal. Alternatively, in setting the transmission window for the corresponding PDCP PDU, it may be excluded from the unconfirmed PDCP PDU set.

Hereinafter, the transmission data processing operation of the PDCP entity of the present invention will be described again using variables.

The transmitting PDCP entity shall maintain a transmission window according to the following state variables VT (A) and VT (MS). (The transmitting PDCP entity shall maintain a VT (A) and VT follow.

- If VT (A) ≤ SN <VT (MS), the sequence number SN is located within the transmission window (a SN falls within the transmitting window if VT (A) <= SN <VT (MS)).

- Otherwise, the sequence number SN is outside the transmission window (a SN falls outside the transmitting window otherwise).

The transmitting PDCP entity shall not transmit any PDCP data PDUs (or PDCP PDUs) whose SN is located outside the transmission window to the lower layer (the transmitting PDCP entity shall not deliver to the lower layer any PDCP Data PDU whose SN falls outside of the transmitting window).

When the PDCP data PDU is delivered to the lower layer, the transmitting PDCP entity sets the SN of the PDCP data PDU to VT (S) and increases VT (S) by one (when Delivering a new PDCP Data PDU to lower layer, the The transmitting PDCP entity shall: - set the SN of the PDCP PDU to VT (S), and then increment VT (S) by one).

In addition, the transmitting PDCP entity may receive a positive response to the PDCP data PDU through the PDCP status report through the X2 interface connected to the secondary base station (the transmitting PDCP entity can not receive a positive acknowledgment a PDCP Data PDU by the following: - PDCP STATUS report from SeNB via X2 interface).

The transmitting PDCP entity should set VT (A) equal to the SN of the PDCP data PDU with SN having the smallest value when receiving a positive response for the PDCP data PDU with SN = VT (A). The SN with the smallest value means the SN of the PDCP data PDU that is located within the range of VT (A) S SN V VT (S) and has not yet received a positive response (when receiving a positive acknowledgment for PDCP with SN = VT (A), the transmitting side shall: - set VT (A) equal to the SN of the PDCP PDU with the smallest SN, whose SN falls within the range VT (A) for which a positive acknowledgment has not been received yet).

Meanwhile, as described above, if the master base station discards the PDCP data PDU, the discarded PDCP data PDU should be regarded as having received a positive response (if the PDCP data PDU is discarded) an PDCP Data PDU received a positive acknowledgment).

In summary, for a dual connectivity split bearer, the receiving PDCP entity of the present invention can perform a reordering operation based on a reordering timer and a receiving window. In this case, when a PDCP PDU having a new SN is received, a reordering operation of the receiving PDCP entity generates a window in the SN direction having a value lower than the SN having the highest value. If PDCP PDUs received outside the window are discarded.

However, in this case, the HFN desync for packets received too early or too late due to a backhaul delay or reordering timer between the wireless communication device (e.g., base station). Problems can arise. The HFN desync problem means that the SN of the PDCP data PDU received from the receiver is erroneously HFN corrected in the operation of adding, subtracting, or leaving HFN value based on the reordering window for HFN correction

Therefore, in order to solve such a problem, the transmission PDCP entity of the present invention sets a transmission window as described above, and updates the transmission window based on reception of a positive response (i.e., an acknowledgment response). In this case, the X2 interface may be used when receiving a positive response from the secondary base station

As described above, the transmission PDCP entity and the reception PDCP entity are functions that can be performed in the same PDCP entity. For example, the operation of the first embodiment of the receiving PDCP entity described above and the operation of the transmitting PDCP entity may be received by one PDCP entity. Alternatively, a PDCP entity may be configured to perform the operations of the second embodiment and to perform a transmission operation to set up a transmission window. Thus, the PDCP entity of the present invention may include only one of the transmit and receive operations, or both transmit and receive operations.

In addition, the case where the PDCP entity of the present invention is configured in the terminal when the PDCP entity is the receiving PDCP entity has been exemplified, and the case where the PDCP entity is configured in the base station in the case of the transmission PDCP entity has been described. However, as described above, this is for the sake of understanding, and the PDCP entity may be applied to both uplink and downlink data transmission and reception, and may be configured to both the base station and the terminal.

A radio communication apparatus configured with the PDCP entity of the present invention described with reference to Figs. 1 to 9 will be described.

10 is a diagram illustrating a configuration of a wireless communication apparatus according to an embodiment of the present invention.

A wireless communication apparatus (1000) including a Packet Data Convergence Protocol (PDCP) entity for processing transmission data, the apparatus comprising: a controller configured to configure dual connectivity and to transmit data received from an upper layer to a lower layer; The PDCP entity includes a transmitter 1020 for transmitting data transmitted to a lower layer and a receiver 1030 for receiving a response signal for the transmitted data, wherein the PDCP entity includes a plurality (PDCP) data unit (PDCP PDU) to each of RLC (Radio Link Protocol) entities of a plurality of RLC entities, based on a response signal for at least one PDCP PDU received from each of the plurality of RLC entities Thereby setting a transmission window.

Referring to FIG. 10, the wireless communication apparatus may be a base station or a terminal, and may be a device that transmits and receives data and signals using radio resources.

The wireless communication apparatus 1000 may include a control unit 1010 that configures dual connectivity and includes a PDCP entity as described with reference to FIGS. In addition, the controller 1010 may configure a bearer split structure when configuring dual connectivity.

The transmitting unit 1020 can transmit data, signals, and the like to the receiving apparatus.

The receiving unit 1030 may receive data and signals transmitted from the receiving apparatus, and may receive a response signal to the transmitted data.

Here, the receiving apparatus may be a counterpart terminal or a base station that performs communication with the wireless communication apparatus, and refers to a device that performs communication using radio resources.

The PDCP entity included in the wireless communication apparatus 1000 of the present invention may include at least one PDCP PDU (Packet Data Convergence Protocol Protocol data unit) in each of a plurality of RLC (Radio Link Protocol) entities having dual connectivity for one radio bearer, And may set a transmission window based on a response signal for at least one PDCP PDU received from each of the plurality of RLC entities.

Also, the response signal may include information on a PDCP PDU that has been confirmed to be received by the receiving apparatus among the at least one PDCP PDU.

On the other hand, the transmission window can be set based on a sequence number (SN) of at least one unidentified PDCP PDU whose reception has not been confirmed by the receiving apparatus and the total number of sequence numbers that can be allocated to the PDCP PDU have. In addition, the transmission window is set to be equal to or larger than the smallest sequence number based on the PDCP PDU having the smallest sequence number among at least one unidentified PDCP PDU, and the size of the transmission window is set to half of the total number of sequence numbers allocated to the PDCP PDU May be set.

In order to prevent ambiguity of the PDCP PDU that has not been transmitted to the lower layer, a PDCP PDU that can not be transmitted to a plurality of RLC entities may not allocate a sequence number, Lt; / RTI &gt;

In addition, the controller 1010 may control the PDCP entity to set a transmission window based on a response signal when a plurality of RLC entities are in an acknowledged mode.

The control unit 1010 controls each operation that can be performed when the PDCP entity of the present invention transmits and receives data, and controls the operation of the wireless communication apparatus according to performing both transmission and reception operations can do.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (13)

A method for a PDCP (Packet Data Convergence Protocol) entity to process transmission data,
Configuring a plurality of Radio Link Protocol (RLC) entities and dual connectivity for one radio bearer;
Transmitting at least one PDCP PDU (Packet Data Convergence Protocol Protocol Data Unit) to each of the plurality of RLC entities;
Receiving a response signal for the transmitted at least one PDCP PDU from each of the plurality of RLC entities; And
And setting a transmission window based on the response signal. The method according to claim 1,
Wherein the PDCP entity is configured in at least one of a terminal and a base station to process transmission data. The method according to claim 1,
The response signal may include:
And information on a PDCP PDU that has been confirmed to be received at the receiving apparatus among the at least one PDCP PDU. The method according to claim 1,
The transmission window includes:
(SN) of at least one unconfirmed PDCP PDU whose reception has not been confirmed by the receiving apparatus, and a total number of sequence numbers that can be allocated to the PDCP PDU. 5. The method of claim 4,
The transmission window includes:
A PDCP PDU having a smallest sequence number among the at least one unacknowledged PDCP PDU is set to be equal to or larger than the smallest sequence number,
Wherein the size of the transmission window is set to a half of a total number of sequence numbers allocated to the PDCP PDU. The method according to claim 1,
The PDCP PDUs that can not be transmitted to the plurality of RLC entities,
The sequence number is not assigned, or the transmission window is set as being received at the receiving apparatus when the transmission window is set. The method according to claim 1,
The step of receiving the response signal and the step of setting the transmission window,
Wherein the RLC entity is controlled to be activated or deactivated based on a mode of the plurality of RLC entities. 1. A wireless communication device comprising a Packet Data Convergence Protocol (PDCP) entity for processing transmission data,
A controller configured to configure dual connectivity and to transmit data received from an upper layer to a lower layer;
A transmitter for transmitting data transferred to the lower layer; And
And a receiver for receiving a response signal to the transmitted data,
Wherein the PDCP entity comprises:
The method comprising: transmitting at least one PDCP PDU (Packet Data Convergence Protocol Protocol Data Unit) to each of a plurality of Radio Link Protocol (RLC) entities configured with the dual connectivity for one radio bearer, And sets a transmission window based on a response signal to at least one PDCP PDU transmitted. 9. The method of claim 8,
The response signal may include:
And information on a PDCP PDU that has been confirmed to be received by the receiving apparatus among the at least one PDCP PDU. 9. The method of claim 8,
The transmission window includes:
(SN) of at least one unacknowledged PDCP PDU whose reception has not been confirmed by the receiving apparatus and the total number of sequence numbers that can be assigned to the PDCP PDU. Device. 11. The method of claim 10,
The transmission window includes:
A PDCP PDU having a smallest sequence number among the at least one unacknowledged PDCP PDU is set to be equal to or larger than the smallest sequence number,
Wherein the size of the transmission window is set to a half of a total number of sequence numbers allocated to the PDCP PDU. 9. The method of claim 8,
The PDCP PDUs that can not be transmitted to the plurality of RLC entities,
The sequence number is not allocated, or the sequence number is set to be received by the receiving apparatus when the transmission window is set. 9. The method of claim 8,
Wherein the PDCP entity comprises:
And sets the transmission window based on the response signal when the plurality of RLC entities are in an acknowledged mode.

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